Man Kills Officer After Argument Over Face Mask At New Orleans School KEY POINTS Martinus Mitchum was working security during a basketball game at George Washington Carver High School John Shallerhorn entered the school without a mask and got into an argument with a staffer over it Shallerhorn had also robbed a man at gunpoint in the school’s parking lot In a horrific incident, a Tulane University police officer was killed by a man who refused to wear a face mask, in keeping with COVID-19 measures, at a school in Louisiana. John Shallerhorn walked into the gym at George Washington Carver High School in New Orleans during a basketball game Friday, but a staffer blocked him for not wearing a mask.